System of rectification



March 6, 1928. 1,661,585

F. TRANSOM SYSTEM OF RECTIFI CATION Filed April 2. 1925 Patented Mar. 6, 1928.

UNITED STATES PATENT OFFICE.

FREDERICK TRANSOM, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO COOPER HEWITT ELECTRIC COMPANY, OF HOBOKEN, NEW JERSEY, A. CORPORA- TION OF NEW JERSEY.

SYSTEM OF BECTIFICATION.

Application filed April 2, 1925. Serial No. 20,180.

My invention relates to apparatus for converting alternating currents of electricity into direct, or continuous direction currents. More particularly the invention utilizes the properties of What is .known in the art as a hot cathode rectifier tube, as improved, described and claimed in an application for United States Letters Patent. Serial No. 578,131, filedJuly 28, 1922, by Earl H.

' Rollinson.

One object of my invention is to increase both the life run and load capacity of such tubes without undue heatin "Another object is to equalize temperature strains on the electrode seals. Other objects and advantages will appear as the invention is described in connection with the accompanyin drawings, which form a part of, this speci cation, and in which The single figure shows diagrammatically a system of connections used in my invention.

In the drawing 1 represents a rectifier tube, as modified by the improvements of the Rollinson ap hcation, above referred to, one feature oi which is that the tube dispenses with a heating filament entirel Thls tube is shown connected into a sing e wave, single phase rectifier circuit, but the improvements here disclosed may readily be applied to circuits for the rectification of both waves of an alternating current, either single phase, or any of the several well known polyphase circuits, by those J5 skilled in the art.

The source of supply shown is a transformer T, provided with two sections, 10 and 11. Section 10 is the load section and 11 is a small load ca acity portion used solely'for excitation of the primary of a high tension, high frequency coil H. C. Starting at terminal 16, a wave in the right direction to pass through tube 1 will traverse reactant-e coil R. C. battery B, switch 8, anode 5 and through tube 1 to terminal 9 of the transformer. The tube 1 contains a gas of the argon group at low pressure and is made one way conductive by an initial excitation, or ionization, set up by a high tension, high frequency current which is derived from coil H. C., as shown in the diagram, but any other high frequency source of current operating at a suitable potential may be substituted equally well for the means shown.

This initial ionization is accomplished by closing switch 6 on contact 13, which impresses a high tension, high frequency current from the secondary of coil H. C. across the electrodes 3, 4. Under these conditions 6 when load switch 8 is closed a current will start in the tube, flowing fromanode 5 to one of the electrodes 3 or 4, depending on how the tube is connected into its socket to complete a circuit to terminal 9 of transformer section 10. After this load current is once started switch 6 may be opened and the tube will continue self exciting on load current alone running from anode 5 to electrode3, as a cathode.

Up to this point the conditions of operation of the system are the same as that-described in Rollinson application Serial No. 578,131, referred to above. Itwill be noted, however, that the tube when thus used leaves electrode 4 standing dead, whereas it has just as much current carrying capacity as electrode 3. In order to utilize the full current carrying capacity of the tube and its two ele trodes, 3 and 4, as joint cathodes for ano e 5 I have provided an additional contact point 12 on which the switch 6 may be placed after the period of initial ionization has been accomplished, and the tube is working on a single electrode, 3 for instance. The effect of placing switch 6 on contact 12 will be to provide an additional path for the space current from anode 5 through electrodet, now acting as a cathode,

to the terminal 9 of transformer section 10. In this position switch 6 acts as an equalizer across leads 3 and 4.

It will thus be seen that the improvements disclosed not only allows twice the current through the tube with the same seals, but the additional current flow through electrode 4 has a temperature equalization effect on the base of the tube which tends to more uniform rectification and longer life of the tube.

I have shown at 7 a reversing switch which may be used, if desired, to change the direction of exciting current flow. It is well known that the tension and current waves of an induction coil, such as can be used at H. C. are dissymmetrical at the make and break, and the switch 7 may be used to select the wave train developing the best excitation characteristics. Switches are used to control the relative amounts of current taken u by each of the electrodes 3 and 4 by setting these switches 15 to put in a small amount of resistance 14' in series with one or the other of those electrodes. Such a control conduces to an equal wear of both electrodes, and to this end also the socket should permit occasional changes in the electrode which is initially ionized.

While I have shown only two electrodes 3 and 4 as adapted to be converted into joint cathodes, it is obvious that a 'reater number of electrodesv could be joined up one after the other to take space current in parallel.

It will be noted that when the tube is working on load current it is completely insulated from its eliciting coil by an open circuit at contact 13 and that the load and exciting circuits are always separated by a ga at G. The condenser K may be connecte by switch 17 across the leads 3 and 4 to steady the o eration of the tube in both the starting an running positions.

What I claim as my invention is- 1. In a rectification circuit, a space tube provided with a load anode, a cathode, an exeitin anode, and means for converting the exciting anode to a load cathode.

2. A rectification system, comprising a rectifying circuit and a starting circuit and means for interconnecting said circuits including an electrode which is in the starting circuit exclusively during the startin period, and subsequent thereto in the wor circuit.

3. A rectifier system comprising a thermionic tube provided with a re-entrant stem, an anode and a cathode element, the latter comprising spaced conductors mounted on said stem, and means whereby said conductors may be used to effect either an initial ionization of the tube, or may be used jointly as a cathode element.

Signed at Washington, D. C. this 23 day of March A. D. 1925.

FREDERICK TRANSOM. 

